The present invention relates generally to electrostatic copiers, and more particularly to an electrostatic copier having a novel developing device.
It is known to provide electrostatic copiers with developing devices utilizing a developer that is composed of toner particles and carrier particles. In such devices the developer mix as the mixture of toner particles and carrier particles will hereafter be called, is supplied from a source of the mix to the inlet end of a supply ramp, the inlet end being located higher than the source, for so-called "cascade developing", where the mix is discharged onto the supply ramp so that it can slide down on the same.
In devices of this type the quality of the development of the image depends to a large extent upon the satisfactory maintenance of as uniform as possible a flow of the developer mix on the aforementioned ramp. The manner in which the developer mix is conveyed from the source to the ramp varies in the prior art. A particularly common way of doing this is to use bucket chains; however, because of the discontinuous supply of the developer mix, in which each bucket of the chain dumps its batch of mix onto the ramp and no further mix is supplied until the next bucket arrives, a uniform flow of the developer mix down the ramp is very difficult to obtain, and can be assured only if intermediate storage devices, elongated supply chutes or other elements are utilized, which require much space and are expensive. Other approaches to the feeding of the developer mix, such as feed screws and the like, have not led to an economically satisfactory and completely reliable solution either.